Hard Star Battle answer — September 24, 2026

Full written solution

Every deduction from the walkthrough above, in order. Each technique is explained in the Star Battle strategy guide.

1. Starting position — the grid is split into regions (bold outlines). Each row, column, and region needs exactly two stars, and no two stars may touch.
2. Blocking rule: This position would block too many candidates (row 3, column 2).
3. Blocking rule: This position would block too many candidates (row 4, column 2).
4. Blocking rule: This position would block too many candidates (row 2, column 8).
5. Blocking rule: This position would block too many candidates (row 2, column 9).
6. Three candidates with two adjacent: Isolated candidate must hold a star (row 1, column 9).
7. Mark 1 cell adjacent to stars as X (row 1, column 8).
8. Two-option rule: Cell adjacent to both candidates (row 4, column 8).
9. Two-option rule: Cell adjacent to both candidates (row 4, column 9).
10. Clump analysis (Region 3): candidate clumps can only just supply the remaining stars (row 3, column 4).
11. Clump analysis (Region 8): candidate clumps can only just supply the remaining stars (row 6, column 1).
12. Blocking rule: This position would block too many candidates (row 8, column 2).
13. Clump analysis (Region 9): candidate clumps can only just supply the remaining stars (row 4, column 6).
14. Undercounting: 4 regions fit in cols 1-4, eliminate 5 outside candidates (row 5, column 3).
15. Blocking rule: This position would block too many candidates (row 4, column 5).
16. Three candidates with two adjacent: Isolated candidate must hold a star (row 5, column 5).
17. Mark 3 cells adjacent to stars as X (row 5, column 6).
18. Two-option rule: Cell adjacent to both candidates (row 2, column 5).
19. Two-option rule: Cell adjacent to both candidates (row 2, column 6).
20. Clump analysis (Column 4): candidate clumps can only just supply the remaining stars (row 1, column 3).
21. Clump analysis (Column 4): each clump must supply its full share of stars (row 7, column 4).
22. Mark 4 cells adjacent to stars as X (row 7, column 3).
23. Clump analysis (Column 3): each clump must supply its full share of stars (row 9, column 3).
24. Mark 1 cell adjacent to stars as X (row 9, column 2).
25. Crowding (Row 4): a star here would leave too little room for its 2 remaining stars (row 5, column 2).
26. Clump analysis (Column 2): candidate clumps can only just supply the remaining stars (row 1, column 1).
27. Clump analysis (Row 5): candidate clumps can only just supply the remaining stars (row 6, column 8).
28. Crowding (Row 2): a star here would leave too little room for its 2 remaining stars (row 3, column 3).
29. Column completion: 1 star needed, 1 candidate (row 4, column 3).
30. Crowding (Row 6): a star here would leave too little room for its 2 remaining stars (row 5, column 8).
31. Clump analysis (Column 8): candidate clumps can only just supply the remaining stars (row 8, column 7).
32. Region completion: 1 star needed, 1 candidate (row 3, column 8).
33. Mark 3 cells adjacent to stars as X (row 2, column 7).
34. Row completion: 2 stars needed, 2 candidates (row 2, column 2).
35. Mark 2 cells adjacent to stars as X (row 1, column 2).
36. Region completion: 1 star needed, 1 candidate (row 4, column 1).
37. Row completion: 1 star needed, 1 candidate (row 2, column 4).
38. Mark 2 cells adjacent to stars as X (row 1, column 4).
39. Region completion: 1 star needed, 1 candidate (row 3, column 6).
40. Column completion: 1 star needed, 1 candidate (row 9, column 5).
41. Mark 2 cells adjacent to stars as X (row 8, column 6).
42. Row completion: 2 stars needed, 2 candidates (row 8, column 1).
43. Mark 2 cells adjacent to stars as X (row 7, column 2).
44. Region completion: 1 star needed, 1 candidate (row 6, column 2).
45. Row completion: 1 star needed, 1 candidate (row 8, column 8).
46. Mark 3 cells adjacent to stars as X (row 7, column 7).
47. Region completion: 1 star needed, 1 candidate (row 6, column 9).
48. Mark 1 cell adjacent to stars as X (row 5, column 9).
49. Row completion: 1 star needed, 1 candidate (row 5, column 7).
50. Mark 1 cell adjacent to stars as X (row 6, column 7).
51. Region completion: 1 star needed, 1 candidate (row 7, column 6).
52. Column 6 complete: Mark 1 remaining cells as X (row 1, column 6).
53. Region completion: 1 star needed, 1 candidate (row 1, column 7).
54. Solved! Every row, column, and region has its two stars, none touching.